Crimping slub filaments of thermoplastic polymers

ABSTRACT

This invention relates to a crimped yarn having slubs which comprises one or more thermoplastic slub filaments and one or more thermoplastic drawn filaments of uniform denier which have been false-twist crimped together. The invention also relates to a process for false-twist crimping such a composite yarn.

United States Patent 1191 Braker 1 Oct. 30, 1973 1 1 CRIMPING SLUB FILAMENTS OF THERMOPLASTIC POLYMERS [75] Inventor: James William Braker, Exhall,

Coventry, England [73] Assignee: Courtaulds Limited, London,

England [22] Filed: Oct. 30, 1970 1211 Appl. No.: 85,621 I [30] Foreign Application Priority Data Nov. 21, 1969 Great Britain ..57107/69 [52] US. Cl. 57/140 BY, 57/157 TS [51] Int. Cl...,. D02g 3/34, D02g 3/38 [58] Field of Search 57/34 R, 34 HS, 12,

57/24, 5 1,6,,139,;140 R, 140 BY, 143, 144, 156,157 TS,157MS,157'R,152

[56] 7 References Cited UNITED STATES PATENTS 3,357,171 12/1967 Marshall"; 57/160 3,401,516 9/1968 Chidgey et a1 57/34 HS 1,997,771 4/1935 McGowan 57/144 3,104,516 9/1963 Field 57/34 B UX 3,263,298 8/1966 Holton 57/34 HS X 1 3,332,227 7/1967 Marshall .1 57/160 X 3,477,218 11/1969 Hawtin et a1 57/34 HS X 3,540,204 11/1970 Tanaka et a1. 57/34 HS Primary ExaminerDona1d E. Watkins Atrorney-Davis, Hoxie, Faithfull and Hapgood 57 ABSTRACT This invention relates to a crimped yarn having slubs which comprises one or more thermoplastic slub filaments and one or more thermoplastic drawn filaments of uniform denier which have been false-twist crimped together. The invention also relates to a process for false-twist crimping such a composite yarn.

3 Claims, 3 Drawing Figures I v m mmumaolsn 3.768.245

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Inventor JAMES WILLIAM BRAKER B wank AI $1117 A Home);

1 CRIMPING SLUB FILAMENTS OF THERMOPLASTIC POLYMERS This invention relates to the false-twist crimping of a filament of varying denier (hereinafter referred to as a slub filament) of a thermoplastic polymer, for example fibre-forming polyamide or polyester, It is understood that false-twist crimping is a process in which a filament or filaments are twisted, set in the twisted condition and allowed to untwist.

It is known to apply false-twist crimping to running filaments of uniform denier by passing the tensioned filaments over and in contact with a frictional surface moving transversely of the filaments; The filaments roll on the surface acquiring a false-twist, the twist running back up the filaments into a heat-setting. zone where the filaments are. set in the twisted configuration. After losing contact with the frictional surface, the filaments are allowed to untwist and then exhibit a helical crimp; The apparatus for carrying out this process may comprise a take-up roller on which the tensioned filament is taken up, the roller carrying a frictional flange which rotates with the. roller, and arranged so that the filament approaching the roller makes contact with the flange. Alternatively the running, tensioned filament may pass through a tube rotating about its axis and make contact with a. frictional lining, or lips, of the tube and be false-twisted by this contact. i

. It is also known to apply false-twist crimping to running filaments of uniform denier by using a rapidly re-' volving tube with a guide extending across the bore of The invention includes a crimped yarn comprising a bundle of helically crimped thermoplastic slub filaments together with a bundle of helically crimped thermoplastic drawn filaments of uniform denier. The bundles are frequently entangled in the yarn even when the drawn filament bundle entering the false-twist crimping process is twisted, say by up to two turns per inch. The entanglement serves to hold together the component filaments of the yarn which may then be further processed, for example knitted or woven, without added twist. Alternatively the yarn may be twisted to consolidate it, the low twist inserted by collecting the yarn over-end onto a bobbin, say up to two turns per inch,

serving for many purposes, but higher twists may also be employed.

According to a further aspect of the invention a process of making a crimped yarn having slubs comprises feeding under tension and at similar linear speeds, one or more thermoplastic slub filaments and one or more thermoplastic drawn filaments of uniform denier to a take-up device, intermediately false-twisting the filaments together, heat-setting the filaments in the twisted condition and allowing the filaments to untwist.

the tube. The filament to be false-twisted is led from a supply package, into the tube, is looped once around the guide and is then passed out of the tube to a collection package.

Attempts have been made to make use of the known processes and apparatus in false-twist crimping a slub filament but the imparted crimp has been found to be irregular and accompanied by a prohibitive number of filament breakages. These deficiencies increase as the lengths of the slubs increase and are pronounced at slub lengths over 5 centimetres. The irregular crimp is probably explained by' the different response of the thick and thin portions of the filament to tension, the former being more likely to yield. In the frictional false,- twisting process the slub filament skips on the frictional surface and acquires only a non-uniform crimp from the intermittent contact. The more damning fault of frequent filament breaks probably stems from the sudden variations in the tension or snatching of the filament arising from the filament skipping on the frictional surface. The slub filament is also subjected to sudden variations in tension when looped over the guide of the rapidly revolving twist tube of the alternative process.

This invention is concerned with a false-twist crimped yarn having slubs, which may be made more easily.

According to one aspect of the present invention a crimped yarn having slubs comprises one or more thermoplastic slub filaments and one or more thermoplastic drawn filaments of uniform denier which have been false-twist crimped together.

Preferably the filament or filaments of uniform denier contribute at least 10 per cent by weight of the yarn.

As regards the false-twisting process, the two filaments together, or the two bundles of filaments together, maintain better contact with a frictional surface than a slub filament or bundles of slub filaments alone, so that a more uniform crimp is imparted to the doubled filaments and variations in tension and the tendency to snatch are reduced, decreasing the frequency of breaks.

A similar improvement is obtained in an alternative false-twisting process in which the filaments or bundles are false-twisted in passing in a loop over a rapidly rotating guide. Once again the presence of the drawn filament of uniform denier, or bundle of such filaments, reduces the amplitude of variations in tension on the filaments or bundles thereof.

Yarn in accordance with the invention may be used in knitting and weaving processes and will exhibit its crimped and slub characteristics in the fabric.

The invention is illustrated in the following Examples and by reference to the accompanying drawing.

FIG. 1 is a schematic diagram of apparatus for falsetwist crimpingv yarn according to the invention;

FIG. 2 is a view in vertical section of the spinner tube shown also in FIG. 1;

FIG. 3 is an enlarged view of a small length of yarn according to the invention.

EXAMPLE 1 A twistless bundle 1 of ten slub filaments, had a minimum denier of 43, a maximum denier of 105 and an average denier of 60. The slub length varied from 68.5 to

89 centimetres with an average of 76 centimetres, whilst the peak deniers were separated by at least 103 centimetres and at most by 124 centimetres with an average separation of l 14 centimetres. This bundle l was fed, at 73 metres per minute by a pair of feed rolls 2 and combined with a denier bundle 3 of 16 drawn filaments of uniform denier. The bundle 3 was advanced at the same linear speed as the bundle l by a further pair of feed rolls 4. The combined bundle was fed to a take-up device 5 by way of a false-twist spinner tube 6 having an internal guide 7 around which the combined bundle was looped. The spinner tube 6 was rotated at 170,000 revolutions per minute about an axis collinear with the longitudinal axis of the combined bundle and the take-up device 5 had a peripheral speed of 68 metres per minute.

A heater 8 was set about the yarn path upstream of the spinner tube 6, to set the twist (60 turns per inch) running back along the yarn from the spinner tube 6. The heater 8 was 45 centimetres long and developed a temperature of 195 C.

The yarn leaving the false-twist spinner tube 6 was allowed to untwist and was passed from the take-up device 5 to a bobbin collection device (not shown). The finished yarn had an obvious crimp and slubs. As shown in FIG. 3, the slub filaments la were entangled with the uniform filaments 3a.

It proved impossible, using the same equipment, to false-twist continuously the bundle of slub filaments alone. breakages occurred too frequently.

EXAMPLE 2 The process of Example 1 was repeated with the 70 denier bundle 3 of 16 drawn filaments replaced a) by a 20 denier bundle of three filaments of uniform denier, and b) by a 40 denier bundle of six filaments of uniform denier. In both cases, a crimped yarn having slubs was made continuously with a much reduced frequency of breaks and ofa more uniform crimp compared with attempts to false-twist the bundle of slub filaments alone.

When the filaments of uniform denier contribute at least 10 percent by weight of the yarn, the process may be operated with so few faults that it is commercially acceptable. The slub appearance of the yarn is significantly diminished as the content of filaments of uniform denier is increased above 55 per cent by weight, but fancy yarns of various appearances are available as the relative proportions of the two kinds of filaments in the yarn are varied.

What is claimed is:

l. A crimped yarn having slubs, comprising at least one helically crimped thermoplastic slub filament and at least one helically crimped thermoplastic drawn filament of uniform denier.

2. A crimped yarn having slubs, according to claim 1, in which the uniform denier material contributes at least 10 per cent by weight of the yarn.

ments to untwist. 

1. A crimped yarn having slubs, comprising at least one helically crimped thermoplastic slub filament and at least one helically crimped thermoplastic drawn filament of uniform denier.
 2. A crimped yarn having slubs, according to claim 1, in which the uniform denier material contributes at least 10 per cent by weight of the yarn.
 3. A process for making a crimped yarn having slubs, comprising feeding under tension and at similar linear speeds, at least one thermoplastic slub filament and at least one thermoplastic drawn filament of uniform denier to a take-up device, intermediately frictional false-twisting the filaments together, heat-setting the filaments in the twisted condition and allowing the filaments to untwist. 